People's preferences for a partner's height appear to play a major role in selecting a mate, according to a new study. Based on the average heights of men and women in Western nations, two of every 100 couples should include a woman who is much taller than her male partner. But the actual frequency of such couples is much lower, Gert Stulp and colleagues at the University of Groningen in the Netherlands reported online Jan. 16 in the journal PLoS One.